Browse: Departments   Dates   Agencies  

CFR Citation: 50 CFR Part 17

RIN ID: RIN 1018-AI68

NOTICE: Part II

DOCUMENT ACTION: Final rule.

SUBJECT CATEGORY: Endangered and Threatened Wildlife and Plants; Determination of Threatened Status for the California Tiger Salamander; and Special Rule Exemption for Existing Routine Ranching Activities

DATES: This rule is effective September 3, 2004.

DOCUMENT SUMMARY: We, the Fish and Wildlife Service (Service), determine threatened status for the California tiger salamander (Ambystoma californiense), under the Endangered Species Act of 1973, as amended (Act). The California tiger salamander, Central population is threatened by habitat destruction, degradation, and fragmentation due to urban development and conversion to intensive agriculture. We also finalize the 4(d) rule for the species rangewide, which exempts existing routine ranching activities.

SUMMARY: Interior Department, Fish and Wildlife Service,

SUPPLEMENTAL INFORMATION

We, the Fish and Wildlife Service (Service), determine threatened status for the California tiger salamander (Ambystoma californiense), under the Endangered Species Act of 1973, as amended (Act). We also finalize the 4(d) rule for the species rangewide.

We will also soon publish a proposed rule designating critical habitat for the Central California tiger salamander in 20 counties in California.

This rule satisfies the final portion of the settlement agreement approved by the Court on June 6, 2002, in Center for Biological Diversity v. U. S. Fish and Wildlife Service (No. C02055WHA (N.D. Cal.). The settlement agreement required us, among other things, to submit a proposal to list the California tiger salamander throughout its remaining range in California (except for the Santa Barbara County and Sonoma County Distinct Population Segments) for publication in the Federal Register on or before May 15, 2003, and to submit a final determination on that proposed rule for publication in the Federal Register on or before May 15, 2004. Throughout this rule we will refer to the final population addressed by the settlement agreement as the Central California tiger salamander. References to the rangewide CTS population include the Sonoma and Santa Barbara populations as well as the Central population addressed in the settlement agreement.

On May 14, 2004, the Assistant Secretary for Fish and Wildlife and Parks at the U.S. Department of the Interior requested from the Court a sixmonth extension of the May 15, 2004, deadline pursuant to 16 U.S.C. 1533(b)(6)(B)(i). The request was based upon the Assistant Secretary's assessment that there is substantial disagreement regarding the sufficiency or accuracy of the available data relevant to the determination, including the level of threat due to inadequacy of the existing regulatory structure, projected future habitat losses and their significance, and the sufficiency or accuracy of data concerning extent of population losses and extent of existing populations. The Court granted an extension to July 23, 2004, to allow us time to resolve the issues raised by the information included in the preliminary California Department of Conservation's (CDC) 2004 data on rangeland and agricultural land conversion. This final listing determination has considered the implications of the information in the CDC report for the California tiger salamander. In addition, we have considered all other scientific and commercial information available to us.
Scientific Disagreement Over Availability of Central California Tiger Salamander Habitat Due to Past Conversions

On June 10, 2004, the United States District Court for the Northern District of California granted an extension to the May 15, 2004, deadline for the specific purpose of resolving the issue of whether there was a 14 percent decrease in grazing land versus an increase in such land that would constitute an increase in Central California tiger salamander habitat. The Court also stated that the Service must make its final determination by July 23, 2004. The issue of habitat trend arose from an April 30, 2004, letter from the Central California Tiger Salamander Coalition (Coalition) to the Service stating that new information was available on the California Department of
Conservation's (CDC) Farmland Mapping and Monitoring Program (FMMP) website. The Coalition stated that this new information indicated that grazing land increased by 1,678 ha (4,146 ac) from 2000 to 2002 for ten counties located within the range of the Central California tiger salamander. The Coalition proposed that these new grazing land areas would serve as habitat for the California tiger salamander, which would in turn offset the loss of salamander habitat that is being converted to intensive agriculture. In their letter, the Coalition concluded that the loss of Central California tiger salamander habitat to intensive agriculture was not a threat to the species.

In response to the July 23, 2004, extension, the Center for Biological Diversity (Center) sent a letter regarding the issue of grazing land and urbanization trends as determined by the FMMP data. In their letter, the Center provided information from the most recent reporting period (six counties, 2000 to 2002) and information on 13 counties that did not have 100 percent coverage from 1992 to 2002 (data from counties that had 100 percent coverage were presented in their comment letter dated September 22, 2003). From the most recent data (2000 to 2002), the Center determined that grazing land continued to be lost to development and other land use changes. This trend was also observed when the data were analyzed for all other counties that did not have 100 percent coverage. In their comment letter dated September 22, 2003, the Center also concluded that many other adverse indirect impacts to California tiger salamanders would result from the continued expansion of urbanization.

Thus, while the two groups used the same data from FMMP, they each applied different analyses and came up with different results and conclusions regarding the future threat to the Central California tiger salamander from the conversion of grazing land.

Following the June 10, 2004, hearing, representatives from the Service met with members of the Coalition and the Center on June 29, 2004, to receive clarification from the Coalition on the issue of trends in the acreage of grazing land. At this meeting, the Coalition provided the Service with a report entitled, ``Evaluation of Threats to CTS from Agricultural Conversion.'' This report provided additional information on changes in the acreage of grazing land to intensive agriculture using the FMMP data within their suggested range of the Central California tiger
[[Page 47213]]
salamander. The Coalition's report also discussed the results of meetings with Agricultural Commissioners from six counties to discuss future conversion of grazing land to intensive agriculture within their respective counties.

After reviewing the information provided by the Coalition, the Center, and our own analysis, we found that all approaches comparing total grazing land lost to total grazing land gained for the 10 to 12 year period indicate a net loss of grazing land for that period. Comparing a different set of figures, however, it appears that intensively farmed lands have been fallowed at a greater rate than they have been reconverted over the last 12 years. It is more difficult to determine what this means to the California tiger salamander. It is unlikely that all of the grazing land converted to intensive agriculture was suitable for salamanders, as some of that could simply be reconversion of previously cultivated land, so the magnitude of the loss likely is not as large as the numbers indicate. Similarly, it is unlikely that the grazing land gained from fallowed agricultural land was all suitable for salamanders.

It is unlikely that the grazing lands formerly under intensive agricultural uses would completely regain all value as California tiger salamander habitat because wetlands that provide breeding habitat would have been destroyed as a result of intensive farming, limiting these areas to potential upland habitat. Fallowed agricultural land might, depending on how it is managed, provide estivation habitat or open space for migration depending on its proximity to breeding habitat. Even though the overall rate of conversion of new lands to intensive agriculture may be decreasing in the future (see below), any expansion of lands under cultivation is most likely to expand into areas adjacent to already cultivated areas. Particularly in the San Joaquin Valley, the lands at greatest risk to this expansion are the fringes of the valley floor which are inhabited by the California tiger salamander. Therefore, we conclude that the majority of these newly created grazing areas may have some utility for migration or estivation to the extent they are adjacent to breeding habitat, but that they do not offset the loss of the portion of grazing lands that were suitable California tiger salamander habitat. In addition, neither the Coalition nor the County Agricultural Commissioners concluded that no California tiger salamander habitat would be converted to intensive agricultural uses in the foreseeable future, only that the future rates of conversion are likely to be lower than they have been in the past. We therefore conclude while it may no longer be the primary source that conversion of suitable habitat to intensive agriculture remains a source of cumulative habitat loss and fragmentation which are primary threats to the California tiger salamander.

The FMMP is a valuable tool for assessing changes in land use over time. However, it is also important to use other sources of information when determining past habitat trends because of continued improvements in mapping technologies and the purpose of each reporting service. We found that grazing land has been lost due to urbanization, conversions to intensive agriculture, and other land uses. We expect these land use trends to continue largely due to the projected increase in human population and development, as well as subsequent expansion of intensive agriculture, as described in this rule.

The areas where acreage of grazing land increased represented 80,267 ha (198,344 ac) over the 10year period on a countywide basis. Approximately 60,926 ha (150,552 ac, 76 percent) of this increase is attributable to cultivated agricultural lands that were fallowed. The grazing land increases reported by FMMP are those lands that have been fallowed for at least three reporting periods or 6 years. Other grazing lands had been previously mapped and reported as urbanized areas, mines, or lowdensity residential developments, which accounted for 17,608 ha (43,511 ac, 22 percent) of the increase in grazing land. Many of these data, including much of the recent data available from FMMP (2000 to 2002), indicate that the increase in grazing land areas are due to improvements in digital imagery that allowed for a more precise distinction between urban boundaries and grazing land (CDC 2002, 2004).

The FMMP data indicate that there was a substantial decline in grazing land in areas, some of which likely represented aquatic and upland habitats for the California tiger salamander and some of which, such as reconverted fallowed agricultural lands, did not. Because of the lower quality of the habitat that may be created from fallowed land, it is unlikely that the increase in grazing land during the 1990s and early 2000s offset the decline in habitat that occurred as a result of the continued trend in grazing land converted to intensive agriculture and development.

Future Conversions to Intensive Agriculture

Using the acreage of grazing land converted to intensive agriculture during this period, the Coalition estimated that 68,119 ha (168,325 ac) of grazing land would be converted to intensive agriculture over the next 25 years based on an estimated rate of loss of 2,725 ha (6,733 ac) per year. The Coalition estimated that this would result in a 4.1 percent loss (68,119 ha, 168,325 ac) of salamander habitat from their estimate of the total amount of available Central California tiger salamander habitat (1.7 million ha, 4.1 million ac). Responses by the Agricultural Commissioners to the interviews indicated that they believed that no more than 405 to 809 ha (1,000 to 2,000 ac) of grazing land would be converted in their counties and that the future loss of grazing land to intensive agriculture would be limited due to lack of water, poor soils, and low crop prices. The Agricultural Commissioners also expected that the majority of future expansions of intensive agriculture would occur around the periphery of other intensive agricultural areas. Summary

After reviewing data from the 20002002 FMMP report, and the supporting information submitted by the Center and the Coalition, we conclude that the newest data set is consistent with trends identified in our habitat analysis for approximately 1990 through 2000, showing that rates of habitat loss for California tiger salamander from all land use changes have been greater than the rate of other land use types ``converting'' to grazing land. We found that between 20 and 25 percent of the observed increase in grazing lands between 2000 and 2002 is attributable to better mapping technology. We also found that rates of agricultural land being fallowed have been greater than rates of fallowed lands being reconverted to cultivation or natural habitat being converted to intensive agricultural uses. We conclude that the majority of these newly created grazing areas may have some utility for migration or estivation, to the extent they are adjacent to breeding habitat, or even potential breeding habitat if stockponds are eventually installed, but they do not offset the loss of the portion of grazing lands that were suitable habitat for the California tiger salamander habitat; however, rates of habitat conversion to intensive agriculture are likely to be lower in the future than they have been in the past.
[[Page 47214]]
Description and Life History of the California Tiger Salamander

Systematics and species description. The California tiger salamander was first described as Ambystoma californiense by Gray in 1853 based on specimens that had been collected in Monterey, California (Grinnell and Camp 1917). Storer (1925) and Bishop (1943) also considered the California tiger salamander to be a distinct species. Dunn (1940), Gehlbach (1967), and Frost (1985) believed the California tiger salamander was a subspecies of the more widespread tiger salamander (A. tigrinum). However, based on recent studies of the genetics, geographic distribution, and ecological differences among the members of the A. tigrinum complex, the California tiger salamander has been determined to represent a distinct species (Shaffer and Stanley 1991; Jones 1993; Shaffer et al. 1993; Shaffer and McKnight 1996; Irschick and Shaffer 1997; Petranka 1998). The range of this amphibian does not naturally overlap with any other species of tiger salamander (Stebbins 1985; Petranka 1998).

The California tiger salamander is a large and stocky terrestrial salamander with small eyes and a broad, rounded snout. Adults may reach a total length of 208 millimeters (mm) (8.2 inches (in)), with males generally averaging about 203 mm (8 in) in total length, and females averaging about 173 mm (6.8 in) in total length. For both sexes, the average snouttovent length is approximately 91 mm (3.6 in). The small eyes have black irises and protrude from the head. Coloration consists of white or pale yellow spots or bars on a black background on the back and sides. The belly varies from almost uniform white or pale yellow to a variegated pattern of white or pale yellow and black. Males can be distinguished from females, especially during the breeding season, by their swollen cloacae (a common chamber into which the intestinal, urinary, and reproductive canals discharge), larger tails, and larger overall size (Stebbins 1962; Loredo and Van Vuren 1996).

Distribution and genetics. California tiger salamander breeding and estivation habitat includes vernal pools, and seasonal and perennial ponds and surrounding upland areas in grassland and oak savannah plant communities from sea level to about 1,067 meters (m) (3,600 feet (ft)) (Stebbins 1989; Shaffer et al. 1993; Jennings and Hayes 1994; Petranka 1998; California Natural Diversity Data Base (CNDDB) 2003; Bobzien in litt. 2003; Service 2004). Along the Coast Ranges, the species occurs in the Santa Rosa area of Sonoma County, southern San Mateo County south to San Luis Obispo County, and the vicinity of northwestern Santa Barbara County (CNDDB 2003). In the Central Valley and surrounding Sierra Nevada foothills and Coast Range, the species occurs from northern Yolo County (Dunnigan) southward to northwestern Kern County and northern Tulare and Kings Counties (CNDDB 2003). This final rule lists the California tiger salamander rangewide as threatened including the Central California tiger salamander population as required by the court and the former DPSs located in Sonoma and Santa Barbara counties, which were listed as endangered (see Previous Federal Action section below) as well as the remaining population of the California tiger salamander as required by the court.

Other records of tiger salamanders from Lake and Mono Counties outside the range of the Central California tiger salamander have been identified as nonnative tiger salamanders (Shaffer et al. 1993). Salamanders at Grass Lake in Siskiyou County (Mullen and Stebbins 1978) have been identified as the northwestern tiger salamander (A. t. melanostictum) (H.B. Shaffer, University of California, Davis pers. comm. 1998).

We note several historical occurrences of the salamander outside its current range. In the northeastern Sacramento Valley, there is a single occurrence located at the Gray Lodge Waterfowl Management Area in southern Butte County and northern Sutter County, and there is also a single occurrence located in Glenn County; both of these records are from the mid 1960s (CNDDB 2003). There are two records from 1939 and another, from an unknown date, of salamanders observed on the edge of the range in south western San Luis Obispo County (CNDDB 2003; Shaffer and Trenham 2004). There is also a historic record of the California tiger salamander that occurs outside the species' range, which is from Riverside County recorded in the late 1800s. Subsequent surveys have not been able to verify the presence of tiger salamanders from any of those locations (Stebbins 1989; Shaffer et al. 1993; M. Root, USFWS, pers. comm. 2004).

Although the area between Butte County and the Cosumnes River contains suitable vernal pools and has been surveyed extensively, the species has only been recorded along the southern edge of Sacramento County, south of the Cosumnes River (CNDDB 2003). In a survey transect that extended along the west side of the Sacramento Valley from Shasta County to Solano County, containing 35 kilometers (km) (22 miles (mi)) of vernal pool habitat and over 200 pools, California tiger salamanders were recorded only at the Jepson Prairie in Solano County (Simovich et al. 1993). In the East Bay area, the California tiger salamander generally does not occur west of Interstate Highway 680, south of Interstate Highway 580, or north of State Highway 4 in Contra Costa or Alameda Counties (LSA Associates, Inc. 2001; CNDDB 2003). It is likely that the species is uncommon or absent in much of the southernmost San Joaquin Valley because of unsuitable habitat. This includes areas to the south of Los Banos in Merced County, and the foothills of the Sierra Nevada south of Visalia in Tulare County (Shaffer et al. 1993).

The factors that restrict the California tiger salamander in the northern and southern extent of its range are not fully understood (H.B. Shaffer, pers. comm. 2002), but may include low rainfall in the southern San Joaquin Valley and the greater abundance of nonnative predatory fish in the northern Sacramento Valley (Hayes 1977). Studies suggest that the present patchy distribution pattern was caused by a combination of the extreme anthropogenic changes in and around the Central Valley, and the restrictive breeding requirements of the species (Dahl 1990; Fisher and Shaffer 1995; Frayer et al. 1989; Holland 1978, 1998; Jones and Stokes 1987; Shaffer et al. 1993; Trenham et al. 2000). Because there are only a few historic collections of the species made during the 1800s, and the majority of collections have occurred in the last 25 years (CNDDB 2003) subsequent to significant changes in historic habitat types (Shaffer et al. 1993), we do not have good documentation of the historic distribution of the California tiger salamander. We have based the analysis in this listing on estimated current distribution and habitat availability and assumed the available habitat is populated.

Reproduction and larval growth. Adult California tiger salamanders mate in vernal pools and similar water bodies, and the females lay their eggs in the water (Twitty 1941; Shaffer et al. 1993; Petranka 1998). In the East Bay area, California tiger salamanders may lay eggs twice, once in December and the second time in February (Bobzien in litt. 2003). Females attach their eggs singly or, in rare
circumstances, in groups of two to four, to twigs, grass stems, vegetation, or debris (Storer 1925; Twitty 1941). In ponds with little or no vegetation, females may attach eggs to
[[Page 47215]]
objects, such as rocks and boards on the bottom (Jennings and Hayes 1994). After breeding, adults leave the pool and return to small mammal burrows in surrounding uplands (Loredo et al. 1996; Trenham 1998a), although they may continue to come out nightly for approximately the next two weeks to feed (Shaffer et al. 1993). In drought years, the seasonal pools may not form and the adults may not breed (Barry and Shaffer 1994).

The eggs hatch in 10 to 14 days with newly hatched salamanders (larvae) ranging in size from 11.5 to 14.2 mm (0.5 to 0.6 in) in total length (Petranka 1998). The larvae are aquatic. Each is yellowish gray in color and has a broad fat head, large, feathery external gills, and broad dorsal fins that extend well onto its back. The larvae feed on zooplankton, small crustaceans, and aquatic insects for about six weeks after hatching, after which they switch to larger prey (J. Anderson 1968). Larger larvae have been known to consume smaller tadpoles of Pacific treefrogs (Pseudacris regilla) and California redlegged frogs (Rana aurora) (J. Anderson 1968). The larvae are among the top aquatic predators in the seasonal pool ecosystems. They often rest on the bottom in shallow water, but also may be found at different layers in the water column in deeper water. The young salamanders are wary; when approached by potential predators, they will dart into vegetation on the bottom of the pool (Storer 1925).

The larval stage of the California tiger salamander usually lasts three to six months, because most seasonal ponds and pools dry up during the summer (Petranka 1998), although some larvae in Contra Costa and Alameda Counties may remain in their breeding sites over the summer (Alvarez in litt. 2003; Bobzien in litt. 2003; Shaffer and Trenham 2004). The absence of sexually mature paedomorphic larvae (mature adults that retain larval characteristics) suggests that the California tiger salamander is unable to express this life history trait, presumably because most of their evolutionary history has been spent in seasonal vernal pool habitats (Shaffer and Trenham 2004).

Amphibian larvae must grow to a critical minimum body size before they can metamorphose (change into a different physical form) to the terrestrial stage (Wilbur and Collins 1973). Larvae collected near Stockton in the Central Valley during April varied from 47 to 58 mm (1.9 to 2.3 in) in length (Storer 1925). Feaver (1971) found that larvae metamorphosed and left the breeding pools 60 to 94 days after the eggs had been laid, with larvae developing faster in smaller, more rapidly drying pools. The longer the inundation period, the larger the larvae and metamorphosed juveniles are able to grow, and the more likely they are to survive and reproduce (Semlitsch et al. 1988; Pechmann et al. 1989; Morey 1998; Trenham 1998b). The larvae perish if a site dries before they complete metamorphosis (P. Anderson 1968; Feaver 1971). Pechmann et al. (1989) found a strong positive correlation between inundation period and total number of
metamorphosing juvenile amphibians, including tiger salamanders. In Madera County, Feaver (1971) found that only 11 of 30 pools sampled supported larval California tiger salamanders, and five of these dried before metamorphosis could occur. Therefore, out of the original 30 pools, only six (20 percent) provided suitable conditions for successful reproduction that year. Size at metamorphosis is positively correlated with stored body fat and survival of juvenile amphibians, and negatively correlated with age at first reproduction (Semlitsch et al. 1988; Scott 1994; Morey 1998).

Lifetime reproductive success for California and other tiger salamanders is low. Trenham et al. (2000) found the average female bred 1.4 times and produced 8.5 young that survived to metamorphosis per reproductive effort. This resulted in roughly 11 metamorphic offspring over the lifetime of a female. Most California tiger salamanders in this study did not reach sexual maturity until four or five years old (Trenham et al. 2000). While individuals may survive for more than 10 years, many breed only once, and one study estimated that less than five percent of metamorphic juveniles survive to become breeding adults (Trenham 1998b). The mechanisms for recruitment are clearly dependent on a number of factors such as migration, terrestrial survival, and population turnover, whose interaction is not well understood (Trenham 1998b).

Breeding habitat. The salamanders breeding in, and living around, a seasonal or perennial pool or pond and associated uplands utilized during the dry months are said to occupy a breeding site. A breeding site is defined as a location where the animals are able to successfully breed in years of normal rainfall and survive during the dry months of the year. The primary historic breeding sites used by California tiger salamanders included vernal pools and other natural seasonal ponds (Storer 1925; Feaver 1971; Zeiner et al. 1988; Trenham et al. 2000). The species has been found in 10 of the 17 California vernal pool regions defined by KeelerWolf et al. (1998). Vernal pools are an important part of the California tiger salamander breeding habitat in the Central Valley and South San Joaquin regions (CNDDB 2003). Currently, the salamander primarily uses stock ponds in the Bay Area and Coast Range regions, largely due to the destruction of vernal pool habitat in these regions. A number of records in the Santa Rosa area document CTS being found in ditches. The extent of the contribution of these intermittent water bodies has not been specifically studied, however there is no evidence that these areas are used for breeding (Cook in. litt. 2003).

Vernal pools typically form in topographic depressions underlain by an impervious layer (such as claypan, hardpan, or volcanic strata) that prevents downward percolation of water. Vernal pool hydrology is characterized by inundation of water during the late fall, winter, and spring, followed by complete desiccation during the summer dry season (Holland and Jain 1998). Vernal pools support diverse flora and fauna that are adapted to the dramatic seasonal changes in moisture and benefit from the lack of predation by nonnative fish. Twentynine other federally or State listed species within the California tiger salamander's range are vernal pool specialists, including 24 plants, four crustaceans, and one insect (KeelerWolf et al. 1998). California tiger salamanders, like the listed vernal pool crustaceans, inhabit these seasonally inundated habitats. However, listed vernal pool crustaceans require a relatively short period of inundation to complete their life cycle (59 FR 48136; September 19, 1994); therefore, pools that support some crustaceans may not hold water long enough to allow successful metamorphosis of California tiger salamander larvae. In a study of amphibians located in eastern Merced County, California tiger salamander larvae were only observed in the largest vernal pools (Laabs et al. 2001). Unlike vernal pool crustaceans, California tiger salamanders can breed and metamorphose in perennial ponds.

In addition to vernal pools and seasonal ponds, California tiger salamanders also use small artificial water bodies such as stockponds for breeding (Stebbins 1985; Zeiner et al. 1988; Shaffer et al. 1993; Alvarez in litt. 2003; Bobzien in litt. 2003; CNDDB 2003). Stock ponds for cattle, sheep, horses, and other livestock have been, and continue to be, built to supply local water needs, especially in rural grazing lands in coastal and Sierra foothill areas where inexpensive public water or ground water is not available (Bennett
[[Page 47216]]
1970). Stock ponds constructed as water sources for livestock are important habitats for the California tiger salamander throughout its range (H. Shaffer, pers. comm. 2003; P. Trenham, University of California, Davis, pers. comm. 2002). In some areas, stock ponds have largely replaced vernal pools as breeding pools (due to the loss of vernal pools) and provide important habitat for the species. For instance, of the 155 California tiger salamander locality records in the East Bay area (Alameda and Contra Costa Counties) where the wetland type was identified, 85 percent (131 sites) were located in stock ponds (CNDDB 2003).

Management of stock ponds determines their suitability as breeding habitat for California tiger salamanders (Shaffer in litt. 2003). As is true of natural vernal pools, the inundation period of stock ponds can be so short that larvae cannot metamorphose (e.g., when early drawdown of irrigation ponds occurs). However, in contrast to natural vernal pools, stock ponds may contain water throughout the year, or for sufficiently long periods, that predatory fish and bullfrogs (R. catesbeiana) can colonize the pond and establish selfsustaining breeding populations (see Factor C below; Shaffer et al. 1993; Seymour and Westphal 1994) these populations likely affect California tiger salamanders. The presence of bull frogs and fish are negatively correlated with salamander populations and so it is possible that extirpation of the salamander population is likely if fish and other predators are introduced (Shaffer et al. 1993; Seymour and Westphal 1994). Inappropriate management of ponds can threaten California tiger salamander habitat. Natural soil erosion, sometimes increased by pond breaching, berm failure, stock animal impacts, and inadequate management practices can result in increased sedimentation of the pond (Hamilton and Jepson 1940, Prunuske 1987), thereby reducing their quality as salamander habitat. Alternatively, ponds with insufficient turbidity provide inadequate cover for larvae. Stock ponds may be geographically isolated from other seasonal wetlands occupied by California tiger salamanders, and newly created ponds may be located beyond the maximum dispersal distances of juvenile or adult salamanders. However, because the species can live for more than a decade (Trenham et al. 2000), and during this time individuals can migrate between aquatic and upland habitats, colonization of newly created and geographically isolated ponds may be possible, provided the intervening habitat can be successfully traversed by dispersing salamanders (Sweet in litt. 2003).

Once fall or winter rains begin, adults emerge from the upland sites on rainy nights to feed and to migrate to the breeding ponds (Stebbins 1985, 1989; Shaffer et al. 1993). Males migrate to the breeding ponds before females (Twitty 1941; Shaffer et al. 1993; Loredo and Van Vuren 1996; Trenham 1998b). Males usually remain in the ponds for an average of about six to eight weeks, while females stay for approximately one to two weeks. In dry years, both sexes may stay for shorter periods (Loredo and Van Vuren 1996; Trenham 1998b). Most marked salamanders have been recaptured at the pond where they were initially captured; in one study, approximately 80 percent were recaptured at the same pond over the course of three breeding seasons (Trenham 1998b). The rate of natural movement of salamanders among breeding sites depends on the distance between the ponds or complexes of ponds and on the quality of intervening habitat (e.g., salamanders may move more quickly through sparsely covered and open grassland than they can through densely vegetated lands) (Trenham 1998a).

Upland habitat and terrestrial ecology. California tiger salamanders spend the majority of their lives in upland habitats, and cannot persist without them (Trenham and Shaffer in review). The upland component of California tiger salamander habitat typically consists of grassland savannah (Shaffer et al. 1993; Alvarez in litt. 2003; Bobzien in litt. 2003; Service 2004). However, in Santa Barbara and eastern Contra Costa Counties, some California tiger salamander breeding ponds occur in grasslands with scattered oak trees, and scrub or chaparral habitats (Shaffer et al. 1993; Alvarez in litt. 2003; 65 FR 57242). Salamanders most commonly utilize burrows in open grassland or under isolated oaks, and less commonly in oak woodlands (Shaffer et al. 1993).

Juvenile and adult California tiger salamanders spend the dry summer and fall months of the year in the burrows of small mammals, such as California ground squirrels (Spermophilus beecheyi) and Botta's pocket gopher (Thomomys bottae) (Storer 1925; Loredo and Van Vuren 1996; Petranka 1998; Trenham 1998a). Although the upland burrows inhabited by California tiger salamanders have often been referred to as ``aestivation'' sites, which implies a state of inactivity, evidence suggests that California tiger salamanders may remain active in their underground dwellings (Sweet in litt. 2003). Movement within and among burrow systems continues for at least several months after the salamander leaves the breeding site (Trenham 2001; Trenham and Shaffer 2004).

California tiger salamanders cannot dig their own burrows, and as a result their presence is associated with burrowing mammals such as ground squirrels (Seymour and Westphal 1994). The creation of burrow habitat by ground squirrels and utilized by California tiger salamanders suggests a commensal relationship between the two species (Loredo et al. 1996). Active groundburrowing rodent populations probably are required to sustain California tiger salamanders because inactive burrow systems become progressively unsuitable over time. Loredo et al. (1996) found that California ground squirrel burrow systems collapsed within 18 months following abandonment by, or loss of, the mammals. California tiger salamanders use both occupied and unoccupied burrows.

Adult California tiger salamanders have been observed up to 2,092 m (1.3 mi) from breeding ponds (S. Sweet, University of California, Santa Barbara, in litt. 1998), which may be vernal pools, stock ponds, or other seasonal or perennial water bodies. A recent trapping effort in Contra Costa County captured California tiger salamanders 805 m (2,641 ft) to 1,207 m (3,960 ft) from the nearest breeding aquatic habitat (Orloff in litt. 2003). Trenham et al. (2001) observed California tiger salamanders moving up to 670 m (2,200 ft) between breeding ponds in Monterey County. Similarly, in an experimental study, Shaffer and Trenham (in review) found that 95 percent of California tiger salamanders resided within 640 m (2,100 ft) of their breeding pond at Jepson Prairie in Solano County. Based on the Monterey County study, and with the caution that there is limited understanding as regards essential terrestrial habitats and buffer requirements, Trenham et al. (2001) recommended that plans to maintain local populations of California tiger salamanders should include pond(s) surrounded by at least 173m (567ft) wide buffers of terrestrial habitat occupied by burrowing mammals. The distance between the upland and breeding sites depends on local topography and vegetation, and the distribution of California ground squirrel or other rodent burrows (Stebbins 1989).

Metamorphosed juveniles leave the breeding sites in the late spring or early summer. Before the breeding sites dry
[[Page 47217]]
completely, the animals settle in small mammal burrows, to which they return at the end of nightly movements (Zeiner et al. 1988; Shaffer et al. 1993; Loredo et al. 1996). Like the adults, juveniles may emerge from these retreats to feed during nights of high relative humidity (Storer 1925; Shaffer et al. 1993) before settling in their selected upland sites for the dry, hot summer months. Juveniles have been observed to migrate up to 1.6 km (1 mi) from breeding pools to upland areas (Austin and Shaffer 1992).

While most California tiger salamanders rely on rodent burrows for shelter, some individuals may utilize soil crevices as temporary shelter during upland migrations (Lorendo et al. 1996). Mortality of juveniles during their first summer exceeds 50 percent (Trenham 1998b). Emergence from upland habitat in hot, dry weather occasionally results in mass mortality of juveniles (Holland et al. 1990). Juveniles do not typically return to the breeding pools until they reach sexual maturity at two years of age at a minimum (Trenham 1998b; Hunt 1998), and survival to adulthood may be low. Trenham (1998b) estimated survival from metamorphosis to maturity at a site in Monterey County to be less than 5 percent (well below an estimated replacement level of 18 percent). Adult survivorship varies greatly between years, but is a crucial determinant of whether a locality is a source or sink (i.e., whether net productivity exceeds, or fails to reach, the level necessary to maintain the breeding site).

Metapopulation biology may help us predict the effects of future habitat loss and fragmentation for taxa that have a metapopulation structure (Marsh and Trenham 2001 and references cited therein). A metapopulation is a set of local subpopulations within an area, where subpopulations become extinct and are recolonized in the future by migrants from other subpopulations (Hanski and Gilpin 1991; Hanski 1994; McCullough 1996). Regional persistence in such systems depends on the migration of individuals between habitat patches (Trenham 1998b). California tiger salamanders appear to conform to a broadly defined metapopulation structure. In the California tiger salamander system, the spatial arrangement of ponds and the migratory behavior of the animals probably have a substantial influence on pond occupancy and local population persistence (Trenham 1998b). If metapopulation theory is predictive of California tiger salamander behavior, then the direct loss of breeding sites with high production of California tiger salamanders or their isolation from other sites due to habitat fragmentation could result in the loss of other breeding sites that rely on interpond dispersal or the metapopulation structure (Trenham 1998b; Marsh and Trenham 2001).

Number of individuals. The total number of individual California tiger salamanders rangewide is not known. Estimating the total number of California tiger salamanders is difficult due to limited data and understanding concerning the life history of the species. Data on numbers of individual California tiger salamanders are lacking for several reasons, first because the species is difficult to detect, second, because the animals spend much of their lives underground (Storer 1925, Feaver 1971, Shaffer et al. 1993, van Hattem 2004), and third, because only a portion of the total number of California tiger salamanders migrate to pools to breed each year (Trenham et al. 2000). The activity of California tiger salamanders during the majority of the year in these burrows is not well documented and has only recently been studied (van Hattem 2004). In the absence of estimates of the total number of California tiger salamanders, we primarily rely on measures of habitat availability as well as current and future habitat status as an indication of the status of the species.

Previous Federal Action

On September 18, 1985, we published the Vertebrate Notice of Review (NOR) (50 FR 37958), which included the California tiger salamander as a category 2 candidate species for possible future listing as threatened or endangered. Category 2 candidates were those taxa for which information contained in our files indicated that listing may be appropriate but for which additional data were needed to support a listing proposal. The January 6, 1989, and November 21, 1991, candidate NORs (54 FR 554 and 56 FR 58804, respectively) also included the California tiger salamander as a category 2 candidate, soliciting information on the status of the species.

On February 21, 1992, we received a petition from Dr. H. Bradley Shaffer of the University of California at Davis, to list the California tiger salamander as an endangered species. We published a 90day petition finding on November 19, 1992 (57 FR 54545), concluding that the petition presented substantial information indicating that listing may be warranted. On April 18, 1994, we published a 12month petition finding (59 FR 18353) that the listing of the California tiger salamander was warranted but precluded by higher priority listing actions. We elevated the species to category 1 status at that time, which was reflected in the November 15, 1994, Animal NOR (59 FR 58982). Category 1 candidates were those taxa for which we had on file sufficient information on biological vulnerability and threats to support preparation of listing proposals. In a memorandum dated November 3, 1994, from the acting Assistant Regional Director of the Pacific Region to the Field Supervisor of the Sacramento Field Office, the recycled 12month finding on the petition and a proposed rule to list the species under the Act were given a due date of December 15, 1995. However, on April 10, 1995, Public Law 1046 imposed a moratorium on listings and critical habitat designations and rescinded $1.5 million funding from our listing program. The moratorium was lifted and listing funding was restored through passage of the Omnibus Budget Reconciliation Act on April 26, 1996. In the NOR published February 28, 1996 (61 FR 7596), we discontinued the use of different categories of candidates, and defined ``candidate species'' as those meeting the definition of former category 1. We maintained California tiger salamander as a candidate species in that NOR, as well as in subsequent NORs published on September 19, 1997 (62 FR 49398), October 25, 1999 (64 FR 57534) and October 30, 2001 (66 FR 54808).

On January 19, 2000, the Santa Barbara County DPS of the California tiger salamander was listed as an endangered species under an emergency basis (65 FR 3096) and proposed for listing as endangered (65 FR 3110). On September 21, 2000, we listed the Santa Barbara County DPS of the California tiger salamander as endangered (65 FR 57242). On January 22, 2004, we proposed critical habitat for the Santa Barbara County DPS (69 FR 3064).

On February 27, 2002, the Center for Biological Diversity (CBD) filed a complaint in the Northern District of California for our failure to list the Sonoma County Distinct Population Segment of the California tiger salamander as endangered (Center for Biological Diversity v. U.S. Fish and Wildlife Service (No. C02055WHA (N.D. Cal.)). On June 6, 2002, the Court approved a settlement agreement requiring us to (1) make 90day and 12month petition findings on the Sonoma County DPS of California tiger salamander, or to publish an emergency and proposed rules if the DPS faced an emergency under the meaning of the Act's section 4(b)(7), by July 15, 2002 and (2) submit a proposal to list the California tiger salamander throughout its remaining range in California (except
[[Page 47218]]
for the Santa Barbara County and Sonoma County Distinct Population Segments) for publication in the Federal Register on or before May 15, 2003, and to submit a final rule for publication in the Federal Register on or before May 15, 2004. On July 22, 2002, we listed the Sonoma County DPS of the California tiger salamander as an endangered species on an emergency basis and proposed to list the DPS as endangered permanently (67 FR 47726; 67 FR 47758). On March 19, 2003, we listed the Sonoma County DPS of the California tiger salamander as endangered (68 FR 13498) with notice that the Service would consider downlisting or listing the entire species rangewide. On May 23, 2003, we proposed (1) to list the Central California DPS of the California tiger salamander as threatened, (2) to downlist the Santa Barbara and Sonoma DPSs from endangered to threatened, and (3) a 4(d) rule for the California tiger salamander where listed as threatened (68 FR 28648). We also asked for public comment on a number of issues, including whether the three populations should be consolidated into a single rangewide listing. This final rule completes our obligations under the settlement agreement.

Summary of Comments and Recommendations

In the May 23, 2003, proposed rule, we proposed to list the Central California DPS of the California tiger salamander as threatened, and we proposed reclassification of the Santa Barbara County and Sonoma County populations from endangered to threatened (68 FR 28648). In the same notice we also proposed that the special rule under section 4(d) of the Act for the Central California DPS be extended to the Santa Barbara and Sonoma County DPS.

In the proposed rule and associated notifications, we announced six public hearings and requested that all interested parties submit factual reports or information that might contribute to the development of this final rule. The comment period for the proposed rule was initially open from May 23 through July 22, 2003. On July 3, 2003, we extended the comment period for an additional 60 days until September 22, 2003 (68 FR 39892) to accommodate additional public hearings. On September 30, 2003, we reopened the comment period for 30 days until October 31, 2003 (68 FR 56251).

We held a total of 10 public hearings on our May 23, 2003, proposed rule: two on June 17, 2003, in Livermore, California; two on June 18, 2003, in Monterey, California; two on June 19, 2003, in Merced, California; two on July 29, 2003, in Santa Rosa, California; and two on July 31, 2003, in Santa Maria, California. We also organized six informal workshops to inform the public and answer questions regarding the California tiger salamander and the proposed rule: two on June 10, 2003, in Livermore, California; two on June 11, 2003, in Merced, California; and two on June 12, 2003, in Monterey, California. On June 24, 2003, per the request of the Alameda County Agricultural Commission, we attended a county meeting, gave a presentation to the public on the proposed rule, and answered questions regarding the species and the proposal. In addition to the public hearings and public workshops we organized, we attended community forums in Merced, California, on September 12, 2003, and in Modesto, California, on October 24, 2003, to discuss the proposed rule and answer questions. At the forums, we provided information on where to obtain copies of the proposed rule and maps of the areas considered potential habitat for the species.

We produced news releases on the proposed listing and the public hearings and workshops and distributed them to the news media on May 16, 2003, July 3, 2003, and September 30, 2003. Stories based on the news releases and the meetings were produced by the Associated Press (May 16 and October 1); the Santa Rosa Press Democrat (May 18, July 30); the San Francisco Chronicle (May 17); the Santa Barbara News Press (May 17); the Modesto Bee (June 12); the Merced SunStar (June 12 and June 20), and the Stockton Record (June 18).

Written public comments were accepted at all the public hearings, workshops, and the Merced and Modesto meetings and entered into the supporting record for the rulemaking. Oral comments given at the public hearings were also accepted into the supporting record. In making our decision on the proposed rules, written comments were given the same weight as oral comments presented at hearings.

We contacted all appropriate State and Federal agencies, county governments, elected officials, and other interested parties and invited them to comment. This was accomplished through telephone calls, electronic mail correspondence, letters, and news releases faxed and/or mailed to appropriate elected officials, media outlets, local jurisdictions, interest groups, and other interested individuals. We also posted the proposed rule and associated material on both our Sacramento and Ventura Fish and Wildlife Office internet sites following their release on May 16, 2003, July 3, 2003, and September 30, 2003, respectively. We published legal notices on the public hearings and workshops in the Contra Costa Times and TriValley Herald on June 1, 2003; the Merced SunStar, Monterey Herald, Santa Barbara NewsPress, San Luis Obispo Telegram Tribune, and Salinas Californian on June 2, 2003; the Pinnacle Newspaper on June 5, 2003; and in the Santa Rosa Press Democrat on July 19, 2003.

We received a total of 1,955 comment letters and electronic mail correspondences (emails) during the three comment periods. Comments were received from Federal, State, and local agencies, Federal and State lawmakers, and private organizations and individuals. We reviewed all comments received for substantive issues and comments, and new information regarding the Central California tiger salamander, the proposed special rule to exempt routine ranching activities, the proposed downlisting of Santa Barbara County and Sonoma County DPSs, and on the appropriateness of a single rangewide designation or combinations of designations. Similar comments were grouped into several general issue categories relating specifically to the proposed rule and are identified below. Some of the comments expressed support for a listing of the Central California tiger salamander. Others opposed a listing. Substantive information supporting each position was incorporated into this final rule. All comments on the proposed reclassification of the Santa Barbara County and Sonoma County DPSs are addressed in this final determination.

Peer Review

We asked 28 scientists, researchers, and biologists who have knowledge of California tiger salamanders, or amphibians generally, to provide peer review of the proposed rule. Eleven of the 28 individuals who were asked to act as peer reviewers submitted comments on the proposed rulemaking. Based on our analysis, all 11 peer reviewers supported the listing of the Central California tiger salamander as threatened. Two of the peer reviewers stated that the proposed exemption for routine ranching activities as written in the proposed rule lacked sufficient biological rationale or did not provide a conservation benefit to the California tiger salamander and stated that it is inappropriate to consider applying it to the Sonoma and Santa Barbara DPSs, while six were generally in support of
[[Page 47219]]
the proposed 4(d) rule. Some peer reviewers suggested ways to improve the conservation aspects of this proposed exemption. Additionally, peer reviewers provided additional documentation of threats to the species and potential conservation measures. This information has been incorporated into the final rule.

Because we relied on unpublished genetics studies for this rule, we also requested peer review from nine universities on the mitochondrial DNA (mtDNA) study of California tiger salamander conducted by Dr. H.B. Shaffer and Dr. P.C. Trenham of the University of California at Davis (report cited as Shaffer and Trenham 2002). Three of the nine agreed to review the report. The peer reviewers had a few technical comments and suggestions; however, all three concluded that the methods and analyses used in this genetic research were appropriate and felt that the conclusions drawn by Dr. Shaffer and Dr. Trenham were appropriate and defensible. One of the peer reviewers also concluded that the data demonstrated that California tiger salamander hybridization with non native tiger salamanders posed a considerable threat to the species. The study by Shaffer and Trenham has recently been accepted for publication (Shaffer et al. in press).
Summary of Comments and Responses for the Proposed Downlisting of the Santa Barbara and Sonoma County Distinct Population Segments

Eight of the 11 peer reviewers who submitted comments on the proposed rule specifically addressed the proposed reclassification of the Santa Barbara and Sonoma County DPSs. Several stated that the proposed reclassification was not consistent with available information on the status and threats to the Santa Barbara and Sonoma County DPSs. One peer reviewer stated that, although it appeared counterintuitive to change the listing designation without data showing some improvement in status, the reclassification may be warranted if the change would allow routine ranching activities.

State Agencies

We received comments from the California Department of Food and Agriculture (CDFA). The issues raised by CDFA are addressed below.

CDFA Comment 1: The proposed rule to list the Central California tiger salamander should include a full discussion of the potential economic impacts associated with the proposed rule. The proposed listing will likely create a regulatory burden for landowners who convert rangeland to other forms of agriculture. Economic burdens to landowners need to be evaluated and mitigated.

Our Response: Under section 4(b)(1)(A) of the Endangered Species Act of 1973, as amended (Act) (16 U.S.C. 1531 et seq.), we must base a listing decision solely on the best scientific and commercial data available regarding the likelihood that the species meets the definitions of threatened or endangered as defined in the Act.

CDFA Comment 2: The relative importance of stressors to the Central California tiger salamander should be described.

Our Response: As described in more detail below, the California tiger salamander is at risk due to: (1) Habitat loss, degradation, and modification from land conversion and alteration; and secondarily to: (2) predation from nonnative species; (3) inadequacy of existing regulatory mechanisms; and (4) hybridization with nonnative tiger salamanders. Thus, the California tiger salamander is appropriately considered to be threatened by conditions identified under four of the five factors and meets the definitions of threatened, regardless of having a relatively extensive distribution. The threat of hybridization with nonnative tiger salamanders is a particularly severe threat in the Central Coast Range and Bay Area regions and, to a lesser extent, the Central Valley region. We consider the other threats to be secondary, but still material to the status of the DPS (see Factor E below).

CDFA Comment 3: References in the proposed rule used to describe adverse impacts to the salamander need to be documented. CDFA indicated that it has recently completed a risk assessment of the use of rodenticides on threatened and endangered species.

Our Response: As stated in the proposed rule, the complete file for the rule is available for inspection, by appointment, during normal business hours at the Sacramento Fish and Wildlife Office. In addition, the proposed rule stated that all comments received during the comment period were available for public review. The complete file for this rule is available for inspection, by appointment, during normal business hours at the Sacramento Fish and Wildlife Office.

The Service received a copy of the risk assessment entitled, ``Ecological Risk Assessment for GrainBased FieldUse Anticoagulant Rodenticides Registered by the California Department of Food and Agriculture for Special Local Needs'' (Silberhorn et al. 2003). The study was an ecological risk assessment that focused on four specific anticoagulant rodenticides and their potential for effects to non target birds and mammals through secondary poisoning (e.g., poisoning through consumption of prey killed by the toxin). The primary target species for these rodenticides is the California ground squirrel, with mortality of exposed squirrels caused by internal hemorrhaging. Secondary poisoning of nontarget species, such as canids or raptors, may result from preying on moribund animals or scavenging on carcasses. The ecological risk assessment did not examine potential effects to amphibians, and California tiger salamanders do not consume dead or dying rodents. The Service has determined that the results of this ecological risk assessment provide little information on the potential risk to California tiger salamanders as the result of direct or indirect effects of rodenticide use.

Summary of Public Comments and Responses

We address other substantive comments and accompanying information in the following summary. Many of the public comments on the proposed downlisting of the Santa Barbara and Sonoma DPSs were similar to, and are included in, the summary of public comments and responses for the Central DPS. In addition to those, commenters raised the issues described below regarding the proposed reclassification of the Santa Barbara and Sonoma County DPSs. All substantive information provided by commenters has been evaluated in the process of making this final determination and has been incorporated into the final rule as appropriate.

Issue 1Distribution, Habitat, Threats, and Use of Science

Comment 1: Numerous commenters stated that the Central California tiger salamander should not be listed as threatened or endangered because the Central California tiger salamander inhabits a large geographical area or is found in many counties. A few commenters, including local governments, stated that the proposed rule did not present scientific evidence that the Central California tiger salamander was threatened, or likely to become endangered in the foreseeable future, as defined by the Act. One commenter questioned how the Central California tiger salamander could be listed if a large portion of its habitat could be deemed as having beneficial land use practices (ranching activities)
[[Page 47220]]
and these activities were proposed for exemption under the special 4(d) rule.

Our Response: A wide distribution or one that includes a number of counties does not, in and of itself, preclude the need to list a species, subspecies, or DPS under the Act. When making a listing determination, we carefully consider the best available scientific and commercial information regarding the historic and current ranges of the taxon under consideration, as well as the abundance of the species, and the pattern, imminence, and magnitude of threats relative to the species' distribution. After completing such an analysis for the Central California tiger salamander, we believe that the best available evidence supports a threatened listing. All 11 of the peer reviewers who responded agreed with our assessment.

We believe that one of the primary threats to the Central California tiger salamander is habitat destruction, degradation, and fragmentation. Much of this threat is related to losses of habitat to urban development and conversion to intensive agriculture. We believe routine ranching, as identified in the 4(d) rule, is neutral or beneficial for salamanders. Listing the DPS as threatened, while exempting these ranching practices, concurrently increases protection of rangelands from conversion to land uses which eliminate Central California tiger salamander habitat and allows ranchers to continue conducting business in a way that either does not harm or benefits the salamander. Because one of our primary concerns is elimination of Central California tiger salamander habitat, we believe it is appropriate to exempt routine ranching even though it is practiced throughout a large portion of the range of the salamander. As described in Factor C and E below, the Central California tiger salamander is threatened on rangeland by other factors unrelated to habitat loss.

Comment 2: Many commenters including local governments stated that we did not use adequate science in making our decision to propose the Central California tiger salamander as a threatened species. A few commenters stated that the California tiger salamander records from the CNDDB were insufficient because this database lacked observations of the species on private lands.

Our Response: We used the best scientific and commercial information available during the status review process and preparation of the proposed rule to make our listing determination. We used museum records; CNDDB information; GIS coverages documenting the land use changes; unpublished reports by biologists; and peerreviewed articles from scientific journals in making that determination. Additionally, the proposed rule was peerreviewed by 11 scientists, researchers, and biologists with amphibian expertise throughout the United States.

Regarding the lack of occurrence data from private lands, the Service is aware that systematic surveys have not been conducted throughout the range of the species. The CNDDB is the clearinghouse for location and status data collected by State and Federal agencies, consultants, scientists, and other knowledgeable biologists on private, State, and Federal lands. We believe that the data in CNDDB, supplemented by information available in other sources and provided by commenters, represents the best available scientific and commercial information on the distribution of the Central California tiger salamander.

Comment 3: Numerous commenters expressed concern that there was not scientific justification for stating that the California tiger salamander can migrate 1 to 2 miles from aquatic breeding habitat into upland habitat.

Our Response: Adult California tiger salamanders have been observed up to 2.1 km (1.3 mi) from breeding ponds (S. Sweet, University of California, Santa Barbara, in litt. 1998), which may be vernal pools, stock ponds, or other seasonal water bodies. During the comment period, the Service received information about a trapping study of California tiger salamanders in West Pittsburg, California, where, during the first three years of the study, 200 to 446 California tiger salamanders were trapped each year 0.8 km to 1.2 km (0.5 to 0.75 miles) away from potential breeding habitat (S. Orloff, in litt. 2003). Additionally, researchers have marked California tiger salamanders in study ponds and have also captured them using pit fall traps in upland migration studies and have determined that the species can migrate up to 670 m (2,200 ft) from breeding ponds to upland habitat (Trenham et al. 2002; Trenham and Shaffer in review).

Comment 4: Numerous commenters stated that the Central California tiger salamander should not be listed as threatened or endangered because the proposed rule does not have population information that would indicate that the species is declining. Commenters also believed that it was inappropriate for the Service to rely on habitat loss for determining the species' decline. One commenter, after conducting a population estimate of the Central California tiger salamander, concluded that there were 840,000 individuals.

Our Response: Based on a review of the scientific and commercial data, the total number of individual California tiger salamanders is not known. The difficulty of estimating the total number of California tiger salamanders has been documented by a number of biologists (Jennings and Hayes 1994; Shaffer et al. 1993). However, estimates have been made for specific locations in Monterey and Alameda counties (Trenham et al. 2000; Kolar in litt. 2003). The fact that this species spends much of its life underground, only a portion of the total number of animals migrate to pools to breed each year, animals do not always breed in their natal pool or pond, and the California tiger salamander's wide distribution make estimating the total number of California tiger salamanders difficult.

To determine the Central California tiger salamander's listing status, we estimated the current distribution and habitat of the species based on known occurrences, and the projected status of the species in the foreseeable future after review of the threats to the DPS from habitatrelated and other factors (see Summary of Factors Affecting the Species section below). For habitatrelated factors, because of our unde

FOR FURTHER INFORMATION CONTACT Wayne White, Field Supervisor (Attn: CTS) telephone: 916/4146600; facsimile: 916/4146713.